Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 190 · 40 questions

Remember (Find the topic, use the formula): Find the topic and the formula: V = I × R, I = V ÷ R, R = V ÷ I, P = V × I, units = W × h ÷ 1000. Change mA to A and kΩ to Ω before using a formula. Check: put your answer back into the formula.

1. 1.🔺 In the V-I-R triangle, how do we find I? (a) I = R ÷ V (b) I = V + R (c) I = V ÷ R (d) I = V × R
2. 2.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 4100 Ω resistor? (a) yellow-brown-brown (b) yellow-brown-orange (c) yellow-brown-red (d) brown-yellow-red
3. 3.True or false: a resistor has coloured bands. (a) True (b) False
4. 4.🔺 A current of 3 A flows when 9 V is joined across a resistor. What is its resistance (in ohms)?
5. 5.🌈 In the resistor colour code, which number does violet stand for?
6. 6.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
7. 7.🔺 A current of 1 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
8. 8.🔺 A 23.5 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
9. 9.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 5 V supply. What current flows (in mA)?
10. 10.Which of these saves electricity? (a) close the fridge quickly (b) use old filament bulbs (c) leave the TV on standby (d) leave fridge door open
11. 11.🧮 A 22 V battery is joined to 12 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
12. 12.🧮 A 2 V battery is joined to 4 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
13. 13.🔺 A current of 1.5 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
14. 14.📏 How many watts (W) is 4.7 kW?
15. 15.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
16. 16.🔺 A current of 50 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
17. 17.True or false: on an LED, the shorter leg is the cathode (−). (a) False (b) True
18. 18.🔺 In the V-I-R triangle, how do we find R? (a) R = V ÷ I (b) R = V + I (c) R = I ÷ V (d) R = V × I
19. 19.🔺 A current of 0.1 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
20. 20.🧮 Three equal 150 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
21. 21.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a capacitor (c) a diode (d) a buzzer
22. 22.🧾 A 2000 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
23. 23.🧾 A family uses 70 units of electricity in a month and each unit costs ₹6. What is the bill (in ₹)?
24. 24.🔍 Which is the odd one out? (a) leave the TV on standby (b) use LED lamps (c) unplug idle chargers (d) use daylight to read
25. 25.True or false: on an LED, the longer leg is the cathode (−). (a) True (b) False
26. 26.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) True (b) False
27. 27.💡 An LED is joined to a 5 V battery through a 220 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) does not light (b) lights up (c) may burn out
28. 28.🧩 Which component is a resistance knob? (a) motor (b) LDR (c) potentiometer (d) resistor
29. 29.True or false: a capacitor smooths a wobbly supply. (a) False (b) True
30. 30.True or false: an LDR makes a beeping sound. (a) False (b) True
31. 31.True or false: to iron one shirt at a time saves electricity. (a) True (b) False
32. 32.🔺 A current of 0.2 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
33. 33.🔺 A current of 3 A flows when 12 V is joined across a resistor. What is its resistance (in ohms)?
34. 34.🧮 Five equal 25 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
35. 35.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 18000 Ω resistor? (a) brown-grey-orange (b) brown-grey-yellow (c) grey-brown-orange (d) brown-grey-red
36. 36.🧮 A 10 Ω resistor is joined in series with two equal 50 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
37. 37.📏 How many watts (W) is 0.3 kW?
38. 38.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
39. 39.🌈 A resistor has the colour bands brown, brown, orange. What is its value (in ohms)?
40. 40.🧩 Which component beeps for an alarm? (a) motor (b) thermistor (c) diode (d) buzzer

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